May 3, 2013

Researchers Look At Muscle Adaptation In Response To Minimalist Running

Just two months ago, redOrbit learned we had a fairly large and vocal audience within the running community when we published an article on the rise of minimalist running shoes and how, without proper gradual introduction, the risk of injury to the runner is a distinct possibility.

Individuals who commented on the March 7 article represented views on both the pro and con side of the argument for the adoption of the relatively new minimalist footwear. But one thing was clear: barefoot and near-barefoot running, perceived to be a more natural form of the sport and therefore less injurious to feet and legs, is here to stay.

The primary difference between traditional and minimalist shoes lays in the stride used by the runner. A traditional shoe, due to the cushioning, causes the runner to land on the heel. Barefoot and minimalist runners land on the forefoot. This landing difference has a direct effect on how the muscles of the legs and feet respond and develop.

But, exactly, how do the muscles change when adapting to a new running style? This question led researchers at the University of Virginia (UVa) to conduct a new one-of-a-kind study of runners currently transitioning from traditional to minimalist running.

“We want to know what happens to the muscles of the leg and foot when recreational runners make the switch to minimalist footwear,” said Geoffrey Handsfield, a UVa PhD student in biomedical engineering who is leading the study. “Many minimalist shoe manufacturers make claims that their shoes will lead to strengthening the muscles of the calf and feet while avoiding common running injuries. However, there is little scientific evidence supporting these claims.”

The purpose of the study was to learn exactly which muscles are strengthened and which are weakened; which elongate and which shorten; and if some muscles involved in the act of running don´t change at all.

To conduct their study Handsfield and his co-investigators, biomedical engineering professor Silvia Blemker and third-year undergraduate biomedical engineering student Natalie Powers, utilized both static and dynamic MRI in conjunction with motion capture cameras and an instrumented treadmill to track the running technique and muscle tissue adaptations of recreational runners transitioning to the minimalist running technique.

“Most studies and discussions have been about running form and the effects on bones and joints, but we´re taking a different approach,” Handsfield said in a statement. “We think it´s relevant to look at the muscles´ adaptations, which also affect the bones and joints in their interactions.”

Handsfield claims this is among the first longitudinal studies of runners during a transition to a new running technique. Additionally, this is the first study to use advanced imaging to study the effects on muscles as a result of different running techniques.

“Dynamic MRI allows us to image the tissue very rapidly so that we can observe displacements of the muscle tissue as our subject performs a controlled cyclic exercise,” Handsfield said. “We're also using static MRI to determine the subjects´ muscle volumes and lengths before and after their transition to minimalist footwear, allowing us to quantify how their muscles changed with minimalist training.”

It is important to note the purpose of the study is not so the researchers can claim one style of running is better than another. The overall purpose is solely to learn the affects of the change on the muscles runners use. They claim their eventual results could help an individual to make their own decisions with regard to which footwear and running style they wish to adopt.

According to Blemker, “Shoe companies are generally not equipped to undergo fundamental studies aimed at understanding how shoe designs affect muscles.” She continued, “At a university, we are able to focus on this type of research that ultimately both advances our fundamental understanding of muscle adaptation and potentially provides a scientific basis for future shoe designs.”

As of the publishing of this article, the researchers have completed phase one of their study — mapping the muscles of study participants who run in standard footwear. Phase two, soon to begin, will map changes that occur within the muscles as their subject runners begin the transition to the more minimalist footwear. Subject runners for the study range in age from 23 to 30 years and are classified as recreational runners who run between 12 and 30 miles per week.

In addition to receiving UVa “Double ℠Hoo” grant funding, intended to pair a graduate and undergraduate students on research projects, the study benefited from a gift from the Merrell shoe company, a manufacturer of minimalist footwear.

This most recent study was able to take advantage of technology originally developed under a project funded by the UVa-Coulter Translational Research Partnership. Previous studies using this new technology have focused on studying muscles in children with cerebral palsy, adults with knee pain, and elite and collegiate athletes.